E2E and Laser Assisted Electron Impact Studies of Helium Ionization

Grants and Contracts Details


PROJECT SUMMARY Pro'fJosed Research Two experiments on He ionization are proposed. The first, motivated by major disagreements between theory and experiment reported in the literature, will measure out-of-plane (e,2e) angular distributions, for a full 360°, using a special geometry that allows out-of-plane conditions to be combined with the binary peak in a single measurement. Data will be taken in the region of He autoionizing states, both on and off resonance. The results are expected to add new insight into a postulated double scattering mechanism that has been invoked to explain the present disagreement between theory and experiment. This experiment will use an existing (e,2e) apparatus modified to allow the electron gun to move on the surface of a (mathematical) cone. We will collaborate on this experiment with Don Madison's theory group at the University of Missouri, Rolla. The second experiment will investigate helium autoionization in the presence of a laser field. Ejected electron spectra will be measured which will contain "sidebands" separated from the normal autoionization peaks by energies equal to integral numbers of the photon energy. The advantage of this type of experiment is that it isolates the photon-target interaction from the photon-projectile interaction; there is at present poor agreement between experiments that involve both types of interaction and theories that emphasize the photon-projectile interaction. In order to carry out these experiments one of the PI's apparatus will be combined with one of the Co-PI's Nd:YAG lasers. The ejected electron count rate will be increased by modifications to the electron optics and the use of a pulsed helium source. Broader im'fJacts resultinq from the Pro'fJosed Research The research will involve both undergraduate and graduate students at the University of Kentucky. The former will work on a project such as data analysis. The project will provide dissertation material for at least two graduate students. Graduates acquire skills in lasers, electronics, vacuum systems, and computer programming, networking, and interfacing with experiments. They present their work at national and international conferences. Al
Effective start/end date7/1/066/30/10


  • National Science Foundation: $373,796.00


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